Question about steel strength??

[Sodo]

Morningwood you are on it! :laughing::laughing: Note to self, keep on topic, OP wants usable info in his thread...

 

[LD1]

What happened tho this...

".........there is only one way to find out."
"Ok, hold my beer and watch this..

Thats is only for the unknown.

Knowing what you want, its known that if you use 1.5x3 tubing it will fail far before 2x2 would

Wood will add very very little because it will do all its initial deflection barely even adding to the strength. Plus it can have no fixation at its ends. For the same weight it would be much stronger to add steel. Add flat bar at the root of the tine (top and bottom). Maybe weld the top one entirely before welding the bottom to pre-tension it in the upward direction (speaking of wood,,,, its like a woodie ).

If you are intent on minimum weight (and enjoy craftsmanship or making your projects take longer) step the thicknesses of your fork tine material. The root being 1/4" thick then 25% out, switch to 3/16", then 1/8" for the final half. I'd do cuts/welds on 45deg. But you will need full confidence in your welds (not to mention thick forum-skin)! Heh heh,,,,,,, Sorry guys dunno why this came to me.

View attachment 417237

If you like 3x1.5 x 3/16" then adding another 3" x 3/16" plate top and bottom at the root of the fork tine should be stronger than 2x2x1/4. I'd holesaw a few 3/4" holes in the plate center every 4-6 inches and weld up the spots.

Its my opinion that a B7800 will have very much diffuculty bending a 2 x 2 x 1/4". IMHO you can make the 3x1.5 work if you beef up the first 25% or 33%.

Adding a 3/16 plate top and bottom would certainly increase strength ALOT. And would give an overall fork thickness of 1-7/8" thick and 3" wide. So why not just buy a 2x4 or 2x3 tube and save alot of time and effort.

 

[jodebg]

Points well taken. Love your slogan, though!

Would be nice to find a used set of forged forks, but so far I have not found a set.

 

[Sodo]

Knowing what you want, its known that if you use 1.5x3 tubing it will fail far before 2x2 would

Based on the 2x2x1/4" being 1.7 times stronger than 1.5x3x3/16",,,, this is "sort of true". But there is not enough information here to "fail" the 1.5x3 for this application.

The output of the 7800's 3-pt hitch is 1650 lbs at the hitch. This 1650lbs lifting force diminishes rapidly as distance from the hitch increases. I'm going to make a guess that if the 3-pt lift arms are only 10 inches long, that you would have about 825 lbs capacity. Certainly just one tine of the 1.5x3 tines can hold that. At 20 inches long you have 550 lbs capacity at the end. At 40 inches you have 330 lbs capacity.

It's my gut feel that you could use the 1.5x3, and probably 1.5 x 3 x 1/8 if you doubled the first 10 inches. Point being that the forks don't have to be heavy for a SCUT. Solid, forged forklift forks from a 5,000 lb forklift ($200/pair used?) would be overkill but can be free if you know lotsa folks with 'stuff' ,,,,, While they could be 'free' they will require a lot of "fabrication" to "attach", and a lot of effort to move around the yard when NOT on the 3-pt.

Engineering can solve this, by example or theoretical or both. Jode you have options for weight carrying capacity, tare weight of the attachment (which reduces lift capacity as you said), ease of assembly, materials available, these are all considerations. Might be useful to know the thinnest material that can support the output of the 7800, then just double or triple the section.

 

[LD1]

The output of the 7800's 3-pt hitch is 1650 lbs at the hitch. This 1650lbs lifting force diminishes rapidly as distance from the hitch increases. I'm going to make a guess that if the 3-pt lift arms are only 10 inches long, that you would have about 825 lbs capacity. Certainly just one tine of the 1.5x3 tines can hold that. At 20 inches long you have 550 lbs capacity at the end. At 40 inches you have 330 lbs capacity.

That is not how a 3PH works.

A 3PH is a parallelogram style linkage. There is no loss of lift force IF it is kept to a true parallel lift. Which is indeed possible on lots of hitches with adjustment of the linkages and toplink.

You do loose a little force the father from parallel the lift is, but it isnt like a simple lever. If you set up the 3PH so that the pallet forks raise in a level manner (heal raises the exact same amount as the tip), the capacity at the tip is the same as at the ball ends. (provided you have enough weight on the front of the tractor to keep it on the ground).

 

[Sodo]

oops yeah you're right. :ashamed: :ashamed: :ashamed: If the lift goes up 5 inches at the hitch, if goes up 5 inches at the end of 43 inch fork tine. No multiplier.

However the end of a 43 inch tine is probably same as the 7800's wheelbase. With the tractor weight 1800 lbs, 900 lbs on the end of a 43 inch tine might lift the front wheels up.

 

[2458n]

Forks are available 42 inch forks should cost you 100.00. You have to go to a auction or a place that does tow motor work. A real factory has a schedule for replacing used forks. The place I worked at last had the original 40+ year old forks on stuff.

 

[otlski]

Hey Joe,

Three thoughts...

One, Logan steel in Meriden/Wallingford has a walk-in store. All steel is about a buck a pound which is about the best you will get in Connecticut. Large selection.

Two, there are lots of forklift places on the Berlin Turnpike who have old forks laying around. They don't give them away however.

Three, I have seen them on Craig'sList but you really need to use Search Tempest to find them across several listing areas.

Looks like we are finally able to see bare roads around here. In a few weeks grass may be visible. See ya around.

Dan

 

[PILOON]

What will work better is 2 X 4" (1/4") channel with the flat side up and taper the 2" sides back 6" or so at the 'tips'
That is a reasonable priced material, stocked everywhere.
Your biggest challenge will be at the heels where you need good corner bracing (like triangulation with side plates).
On my CUT I designed them to be clamp on to my FEL bucket and I can lift as much as my FEL can handle.
While you said 48" long 28" will lift a 48" pallet if that pallet is evenly loaded.
48 up front is awkward so consider whatever is the shortest you can get away with.
Also with forks the load being way up front of a FEL C. of G. the capacity is way less, like as much as 50%.

OOPs see that you want 3 point, but basics still the same except heel triangulation is less of a problem as that would be offside and less of a hindrance.

As said, capacity will be lower than the actual lift force capabilities with lots depending on load distance from the rear axle.
If pressed I know how to calculate those C of G loads.

PS, I used to sell fork lift trucks.

 

[jodebg]

Hi Dan-

Small world, again. Talk to you more here, than when you pass by.

Yes, it's good to see the snow and ice going in the right direction-away.

Love to have you take a look at the plans that I am thinking about using.

Thinking about modifying the design to fit both the FEL and 3PH, with
removable forks and being able to use as a log skid, as well.

Thanks for the name of the steel seller. The Pine Meadow store charges around 1.30-1.40/lb.

Any names of the pallet fork places that may have old forks?

John

Hey Joe,

Three thoughts...

One, Logan steel in Meriden/Wallingford has a walk-in store. All steel is about a buck a pound which is about the best you will get in Connecticut. Large selection.

Two, there are lots of forklift places on the Berlin Turnpike who have old forks laying around. They don't give them away however.

Three, I have seen them on Craig'sList but you really need to use Search Tempest to find them across several listing areas.

Looks like we are finally able to see bare roads around here. In a few weeks grass may be visible. See ya around.

Dan